/scoreboard objectives add antiJump dummy

execute @a[score_antiJump_min=0,score_antiJump=0] ~ ~ ~ detect ~ ~-.1 ~ air 0 scoreboard players set @s antiJump 1
scoreboard players add @a[score_antiJump_min=1] antiJump 1
execute @a ~ ~ ~ detect ~ ~-.1 ~ air 0 scoreboard players set @s antiJump 1
effect @a[score_antiJump_min=2,score_antiJump=2] levitation 0
effect @a[score_antiJump_min=2,score_antiJump=2] levitation 1 128
scoreboard players set @a[score_antiJump_min=9] antiJump 0
effect @a[score_antiJump=0] levitation 1000000 254